The present invention provides improvements to aerated milk composition, especially yogurt based products, and more particularly, a stirred style and aerated yogurt based product that can be consumed as a flowable beverage.
Yogurt has long been believed to be a healthy food source and thus beneficial to the body in such a way that it is seen to “enhance” the microflora of the gut. Microorganisms in yogurt, including Lactobacillus bulgaricus and/or Streptococcus thermophilus, can help decrease or alleviate symptoms of lactose intolerance. In addition to bacterial cultures, one or more of other optional ingredients can also be added to the dairy ingredients, such as vitamins (for example, vitamin A and/or vitamin D), additional dairy products (for example, cream milk, partially skimmed milk, skim milk, or a combination of any of these), and other ingredients that can increase the nonfat solids content of the food (such as concentrated skim milk, nonfat dry milk, buttermilk, whey, lactose, lactalbumins, lactoglobulins, or whey modified by partial or complete removal of lactose and/or minerals), nutritive carbohydrate sweeteners (such as sugar, invert sugar, brown sugar, refiner's syrup, molasses, high fructose corn syrup, fructose, fructose syrup, maltose, maltose syrup, dried maltose syrup, malt extract, dried malt extract, malt syrup, dried malt syrup, honey, maple sugar, or others), flavoring ingredients, color additives, and/or stabilizers.
In addition to the wide range of ingredients used, yogurt is now available in a wide assortment of varieties of texture, fat content, sweetener type and level, and flavor among other attributes. From a yogurt manufacturing process standpoint all yogurts fall into one of two styles; namely, 1) set yogurts, and 2) stirred style. Within these broad two classifications, numerous yogurt varieties exist.
In the set style, the manufacturer fills cups or containers with an inoculated but unfermented milk base and quiescently holds the filled cups at warm temperatures to allow the yogurt to ferment therein. After the desired fermenting or maturing time, the product is cooled which arrests the culturing activity and also allows the body to set to form the gel-type texture. Set style yogurts have a relatively low initial viscosity (i.e., upon filling of its food package container) and a higher temperature (“temperature of filling”) compared to the viscosity of stirred style yogurt products. As the product ferments and then is cooled, the viscosity of the product increases to final viscosity value that can be well above the initial viscosity.
In the second general category of yogurt products, the yogurt is of a stirred type. In producing stirred yogurt products, the manufacturer 1) ferments an inoculated milk base in bulk, e.g., in large stirred fermentation or culturing tanks, 2) cools the yogurt so formed to arrest the fermentation, and then 3) fills individual yogurt containers with thickened yogurt. Such production facilities are run in a continuous or semi-continuous manner. More specifically, after fermentation to desired acidity and thickness, the yogurt is pumped through cooling heat exchangers to arrest the fermentation. Alternatively, the yogurt can be cooled in a two stage process to reduce shear and maximize the viscosity of the product. In a two stage process the yogurt can be first cooled to 21° C. via a cooling plate, thereafter the yogurt can be cooled to 4° C. via a cooling tunnel. Flavorings and sweeteners can be admixed with the cooled yogurt and the yogurt is charged to containers. Care needs to be taken to minimize the shear imparted to the yogurt in practicing such process steps to minimize the loss of thickness or viscosity built up by the fermentation step. Thus, the stirred style yogurt typically has a higher viscosity than set style yogurts upon filling due to the lower temperature and the thickening affect of yogurt culture. Nonetheless, the stirred style yogurt typically builds or increases substantially in viscosity after filling over time until reaching its intended finish viscosity. Of course, stirred yogurts also come in various styles and product variations.
Most commonly, fruit constituents such as fruit preserves or purees are stirred into the stirred yogurt immediately prior to filling. Such stirred style yogurts comprising intermixed fruit purees are sometimes referred to most frequently as “Swiss” style or, less frequently but equivalently as “Continental” or “French” style. Occasionally, stirred Swiss style yogurts are formulated with high levels of stabilizers with the result that upon refrigerated storage for 48 hours, the yogurt possesses a solid-like consistency, somewhat reminiscent of custard style yogurt. Stirred style yogurts may also be used as a base for beverage products
As can be appreciated from the above description of the numerous styles and flavors within styles of yogurts, product proliferation and differentiation is an important characteristic of commercial yogurt manufacture. In this highly competitive food product category, there is a continuing desire to develop novel products having distinctive visual, taste, and textural variations in order to stimulate interest in yogurt sales. Consumers also value convenience in consuming yogurt and may select yogurt based products that can be consumed as a beverage. In particular, it is believed that many consumers will find aesthetically attractive yogurt based products having a light or aerated texture that are consumed as a flowable product. Yogurt based products that are aerated or whipped can be characterized as having a density reduced from a native range of 1.1 to 1.2 g/cc (depending upon sugar content, fruit content, etc.) to a range of 0.30 g/cc to 1.0 g/cc.
Three primary difficulties are presented by the development of such aerated products characterized by having reduced density. First, unlike frozen dairy products such as ice cream or some aerated frozen yogurt or frozen yogurt containing products, yogurt is traditionally distributed and consumed with live bacterial cultures that require refrigerated distribution (2° C. to 10° C.). As a result of the storage temperature, the foam created by aeration is less stable in a refrigerated yogurt product leading to larger gas cells over time and even some collapse of the foam. Second, additives generally employed to increase initial foam volume in food products such as proteins, hydrocolloids, and other emulsifiers do not produce a sufficiently stable foam in a flowable system and can exhibit undesirable air cell coalescence leading to some collapse of the foam. Third, additives employed to increase initial foam volume and stability over time should not adversely affect other flavor and texture attributes. Notably, proteins added for aeration purposes can create an off-flavor in cultured dairy products.
One approach to overcoming these problems and obtaining a stable aerated milk composition is addition of an emulsifier or emulsifier blend to an unfermented milk base or to a yogurt base when producing a yogurt based product. Description of highly advantageous emulsifiers that are hydrated emulsifier blends and methods for preparing these hydrated emulsifier blends are contained, for example, in commonly assigned U.S. Publication No. 2003/0068406 (Nair et al.) in commonly assigned U.S. Publication No. and 2003/0224089 (Engesser et al.) the disclosures of which are incorporated herein by reference in its entirety. Aerated milk compositions prepared using these emulsifiers have been met with wide consumer acceptance and commercial success. However, these previously disclosed compositions are not flowable and may not be readily consumed without aid of silverware or other utensils.
The present invention is directed toward aerated milk compositions, especially yogurt based products, admixed with selected emulsifiers and stabilizers, that are aerated to provide filling and final viscosities and densities within specified ranges that allow for preparation of unique shake-type products that are flowable and may, for example, consumed without aid of silverware or other utensils.
These and other objects will become increasingly apparent by reference to the following description.